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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
491

Efficacy Evaluation for Melting Treatment of Municipal Incinerator Fly Ash by Electric Arc Furnace in a Steel Mill

Huang, Chien-wen 12 July 2005 (has links)
The objective of this study was to utilize an electric arc furnace ¡]EAF¡^in a steel mill to melt municipal incinerator fly ash ¡]MIFA¡^of different sources ¡]Plants K1 and K2¡^ and evaluate its effectiveness in aspects of environment and economy. The results of full-scale tests have shown that slag thus generated by the EAF was found to be non-hazardous based on the TCLP result and also met the standard of CNS 14602. However, EAF dust thus obtained remained hazardous as it was originally a listed waste by Taiwan EPA. Test results have indicated that this novel treatment technology would not deteriorate the quality of steel billets and bars produced. Moreover, when melting MIFAs from Plant K1¡]with 2.00 wt¢H of MIFA¡^ and Plant K2 ¡]with 3.28 wt¢H of MIFA¡^, the air quality in the steel mill surroundings and off-gas from the stack were all below the regulatory limits. Thus, it would not cause additional pollution problems from this practice. Based on the total capacity of EAFs in Taiwan, it was estimated that these EAFs would be capable of melting fly ash generated by municipal incinerators in Taiwan. From the economic perspective, this melting practice would not lower the production rate of EAF steel-making and increase the tap-to-tap cycle time, consumption of electrical energy, consumption of oxygen, and consumption of graphite electrodes. Furthermore, through this novel practice, the contents of MIFA have turned out to be able to replace some portions of quick-lime and coke powder required for steel-making. Test results have also shown that 1 wt¢H of MIFA injection would generate additional 8.93 kg of slag and 2.76 kg of EAF dust. It was found that an additional cost of NT¢C318 per ton of MIFA treated would be resulted through this practice. This treatment cost is very low as compared with NT¢C8,000 per ton of waste treated by solidification and followed by landfilling. Assuming a melting cost of NT¢C5,000 per ton of MIFA is charged by EAFs, it would save more than ten million NT¢C per year for a municipal incinerator with an annual generation of 5,840 tons of MIFA. On the other hand, for a mini-mill with an annual capacity of 264,000 tons of billets, it would have an additional income of 37 million NT¢C if 3 wt¢H of MIFA is melted while making steel.
492

none

- quan, Yu 02 August 2006 (has links)
none
493

衝撃波流れによって形成される粉塵雲の数値シミュレーション

土井, 克則, DOI, Katsunori, MEN'SHOV, Igor, 中村, 佳朗, NAKAMURA, Yoshiaki 03 1900 (has links)
No description available.
494

Engineering analysis of fugitive particulate matter emissions from cattle feedyards

Hamm, Lee Bradford 12 April 2006 (has links)
An engineering analysis of the fugitive particulate matter emissions from a feedyard is not simple. The presence of an evening dust peak in concentration measurements downwind of a feedyard complicates the calculation of an average 24-h emission flux for the feedyard. The evening dust peak is a recurring event that occurs during evening hours when particulate matter concentration measurements increase and decrease dramatically during a short period of time. The concentrations measured during the evening can be up to 8 times the concentrations measured throughout the rest of the day. There is a perception that these concentration increases are due to increases in cattle activity as the temperature decreases during the evening. The purpose of Objective 1 of this research was to quantify the changes in concentrations based on changes in meteorological conditions and/or cattle activity. Using ISCST3, a Gaussian-based EPAapproved dispersion model used to predict concentrations downwind of the feedyard , the results of this work indicate that up to 80% of the increase in concentrations can be attributed to changes in meteorological conditions (wind speed, stability class, and mixing height.)The total fugitive particulate matter emissions on a cattle feedyard are due to two sources: unpaved roads (vehicle traffic) and pen surfaces (cattle activity). Objective 2 of this research was to quantify the mass fraction of the concentration measurements that was due to unpaved road emissions (vehicle traffic). A recent finding by Wanjura et al. (2004) reported that as much as 80% of the concentrations measured after a rain event were due to unpaved road emissions. An engineering analysis of the potential of the unpaved road emissions versus the total feedyard emissions using ISCST3 suggests that it is possible for 70 to 80% of the concentration measurements to be attributed to unpaved road emissions. The purpose of Objective 3 was to demonstrate the science used by ISCST3 to predict concentrations downwind of an area source. Results from this study indicate that the ISCST3 model utilizes a form of the Gaussian line source algorithm to predict concentrations downwind of an area source.
495

Physicochemical Characteristics and Source Allocation of Asian Dusts Sampled in Penghu Islands

Liu, Yi-chi 25 August 2008 (has links)
In recent years, the Asian dust storms occurred frequently. It was estimated that approximately eight hundred million metric tons of Asian dusts transported to the atmosphere yearly. During the dust storm period, Asian dusts not only induce poor air quality, but also reduce atmospheric visibility and influence human health. In order to investigate the physicochemical characteristics and source allocation of Asian dusts, this study collect the Asian dusts in the Pescadores Islands during the years of 2002~2006. In addition, this study collected top soils in three regions of Inner Mongolia and resuspended the soil samples in a resuspension chamber to analyze their chemical composition. Moreover, this study applied enrichment factor analysis (EF) and grey relational analysis to allocate the potential sources of Asian dusts and compare them with the transportation routes obtained from backward trajectory. During Asian dust storm periods, the concentration of atmospheric particulate matter (PM10) in the Pescadores Islands increased significantly, probably is 3~6 times of PM10 during non-dust storm periods. Among them, coarse particles (PM2.5-10) particularly rose from 10~30 £gg/m3 to 80~130 £gg/m3 and the size distribution changed from bi-modal distribution to single modal distribution of coarse particles during Asian dust storm periods. This study further analyzed the chemical composition of Asian dusts, including water-soluble ionic species, carbon contents, and metallic contents. For fine particles (PM2.5), the order of water-soluble ionic species was SO42- > NH4+ > NO3- > Cl- > Ca2+ > Na+ > K+ > Mg2+ > F-. For coarse particles (PM2.5-10), the order of water-soluble ionic species was Cl- > SO42- > NO3- > Na+ > Ca2+ > NH4+ > Mg2+ > K+ > F-. The carbon contents distributes mainly in fine particles. The major contents of both fine and coarse particles were crustal elements (i.e. Al, Fe, Na, Mg, K, Ca, and Sr). In addition to the analysis of physicochemical characteristics of Asian dusts, this study applied HYSPLIT MODEL to figure out their transportation routes by backward trajectory. According to the backward trajectories, this study compartmentalized Asian dusts storm transportation routes into three categories: Eastward Transportation and Retraced (ETR), Southeasterly Transportation and Circumrotated (STC), and Straight Southeasterly Transportation (SST). Analyzing the spatial and temporary background variables to investigate the influence of transportation routes on Asian dusts¡¦ physicochemical characteristic. This study revealed that the physicochemical characteristics were very similar for same category of Asian dust storms, which can be used to allocate the source regions of Asian dust storms. This study resuspended the soil samples collected in Inner Mongolia inside a resuspension chamber and collected the suspended particles (PM2.5, PM2.5-10) for chemical analysis. Chemical analysis results indicated that the fingerprints of chemical composition for different regions were similar but still distinguishable, which can be used to identify the source areas of Asian dusts. This study further compare and correlate the Asian dusts collected at the Pescadores Islands during Asian dust storm periods with the soils collected in Inner Mongolia chemically by enrichment factor and grey relational analysis. This study further compared the source allocation of Asian dust storms obtained from enrichment factor, grey relational analysis, and backward trajectory and found the results of these three methods were quite similar. For enrichment factor analysis, 88% of similarity was obtained by using two separate reference elements (Al and Fe). The similarity of backward trajectory and grey relational analysis reached as high as 83%. Moreover, the backward trajectory and enrichment factor were similar up to 75%, while the grey relational analysis and enrichment factor were similar up to 69%. Overall, two out of three aforementioned methods can effectively allocate the source regions of Asian dusts by 94%, while all three methods can successfully allocate the source regions of Asian dusts by 56%. Comparison of three aforementioned methods showed that they can be applied to allocate the source regions of Asian dusts.
496

Characterization and formation of particulate nitrate in a coastal area [electronic resource] / by Melissa Cheryl Foster Evans.

Evans, Melissa Cheryl Foster. January 2003 (has links)
Includes vita. / Title from PDF of title page. / Document formatted into pages; contains 236 pages. / Thesis (Ph.D.)--University of South Florida, 2003. / Includes bibliographical references. / Text (Electronic thesis) in PDF format. / ABSTRACT: Particulate nitrates play important roles in the atmosphere. They consist mainly of NH4NO3 and NaNO3, products from the reactions of gaseous HNO3 with gaseous NH3 and sea salt, respectively. The gas-to-particle phase conversion of nitrate changes its deposition characteristics and ultimately changes the transport and deposition rates of the locally produced species. Studies were conducted to develop background information on the particle concentrations and size distributions and the chemistry and kinetics behind the interactions. The predominant nitrate species in the Tampa Bay area was identified as coarse mode NaNO3. NH4NO3 was not detected as it has high volatility at ambient temperatures. Spatial distribution sampling determined a gradient of NaCl and NaNO3 with increased distance from the coastal shore and an increase in the gas-to-particle conversion of nitric acid along a predominant air mass trajectory. / ABSTRACT: The EQUISOLV II thermodynamic equilibrium model was evaluated. It was determined that the model can be used to predict gas and size-distributed particulate matter concentrations. The model was also used to examine the gas-to-particle partitioning of nitric acid to nitrate by NaCl and CaCO3. Both sodium and calcium partitioned nitrate to the particle phase. The magnitude of the partitioning was directly dependent on the equilibrium coefficients. The fine mode percentage of the total nitrate was determined using two methods. The results were used to expand the current data set to account for the coarse mode nitrate, and they indicated that particle nitrate accounted for 9% of the total nitrogen deposition flux to Tampa Bay. The formation of particle nitrate was examined using a nitrate accumulation model. / ABSTRACT: Results indicated that the equilibrium time for particles less than 10 um in diameter was significantly less than their atmospheric residence time, with fastest conversion occurring under the highest relative humidity conditions. This information is vital in the development of atmospheric nitrogen dry deposition estimates, which are used to assess water quality and nutrient loading. These data can be used to determine air-monitoring strategies and to develop models that account for the coarse particle nitrogen species. / System requirements: World Wide Web browser and PDF reader. / Mode of access: World Wide Web.
497

The effectiveness of ventilated sanders in controlling inhalable dusts during scuff sanding on military aircraft /

Patel, Kalpesh B., January 2001 (has links) (PDF)
Thesis--University of Oklahoma. / Includes bibliographical references (leaves 45-46).
498

Interaction between primary alveolar macrophages and primary alveolar type II cells under basal conditions and after lipopolysaccharide or quartz exposure

Kanj, Rania S. January 2004 (has links)
Thesis (Ph. D.)--West Virginia University, 2004. / Title from document title page. Document formatted into pages; contains x, 130 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 120-130).
499

Measurement of community and laboratory-generated airborne particulates using a new sampling method

Farina, Laura 01 June 2010 (has links)
This project resulted from an alleged dust problem affecting the residents in a Florida community. The residents claimed that there were elevated dust levels caused by a rock quarry adjacent to their homes. The purpose of this work was to assess total particulate, respirable particulate, and the coarse content of the sampled particles through traditional NIOSH methods, and using a new, real-time instrument known as the EPAM 5000. Data from the EPAM and NIOSH methods were compared to the EPA's particulate matter standards and the OSHA permissible exposure limits for total and respirable dust. Dust levels using the NIOSH methods were below the limit of detection. There were measurable dust levels in all three size fractions (PM10, PM[subscript 2.5], PM1) for the EPAM. Due to the undetectable levels of the NIOSH method sampling, further sampling in a laboratory environment was conducted in order to compare NIOSH methods with the EPAM 5000 method. The project continued into an aerosol chamber in the USF College of Public Health Breath Lab for further data collection in order to compare results using traditional NIOSH methods with the results obtained from the EPAM 5000. The chamber was associated with a dust generator that released a steady flow of fly ash particulate at a specific revolution per minute (rpm). Each run of data collection sampled approximately 1 m³ of air and persisted for six to seven hours. Four separate runs were conducted, each at a different generation rate of fly ash. There were measurable dust levels using the NIOSH total dust and NIOSH respirable dust methods. There were also measurable dust levels in all three size fractions (PM10, PM[subscript 2.5], PM1) for the EPAM. The results of all methods were compared. The PM[subscript 2.5] and PM1 sampling heads of the EPAM 5000 were compared to the NIOSH respirable dust sampling results. The PM10 sampling head of the EPAM was compared to the NIOSH total dust sampling results. NIOSH 0500 concentration results were within 10% of the EPAM PM10 concentration.
500

Organophosphates and phthalates in air and dust from indoor environments : Method development and applied measurements

Bergh, Caroline January 2011 (has links)
Organophosphate and phthalate esters are polymer additives that are frequently found in air and dust in indoor environments. This thesis describes the development and application of air sampling and selective mass spectrometric (MS) determination of these two compound groups. It also describes the sampling and screening of these compounds in indoor air and dust from different environments and the development and evaluation of a method for the extraction and determination of these compounds in indoor dust. An air sampling method previously used for air sampling of only organophosphate esters, is here demonstrated to be applicable for simultaneous sampling of both phthalate and organophosphate esters. Selective detection using tandem mass spectrometry (MS/MS) showed good results for simultaneous determination of organophosphate and phthalate esters in air. The high selectivity of this technique was especially advantageous when analyzing dust. Comparison of chemical profiles of the organophosphate ester between indoor environments including daycare centers, offices and private homes differed between the types of locations while the phthalate profiles were rather similar. Comparison of concentration levels of these compounds in multi-storey apartment buildings classified as either high or low risk “sick” buildings could not differentiate the two classes of buildings. Further, the studies also points out some potential sources of organophosphate and phthalate esters in these indoor environments. In general the levels of phthalate esters were consistently higher than the levels of organophosphate esters both in air and in dust. Phthalate and organophosphate esters were also determined in a dust standard reference material; seventeen of the targeted compounds were quantified out of which ten had not previously been reported for this reference material. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 3: Submitted. Paper 4: Manuscript.</p>

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